1. Field of the Invention
The present invention relates to a tool, and more particularly to a tool having a rotatable driving head to be adjustably secured to the tool handle with a simplified lock device.
2. Description of the Prior Art
Various kinds of typical tools have been developed and comprise a rotatable driving head provided thereon and adjustable to different angular positions relative to the handle, and selectively lockable to the handle with a lock device.
For example, U.S. Pat. No. 4,463,632 to Parke, and U.S. Pat. No. 6,336,383 to Hung disclose two of the typical tools including a rotatable driving head adjustably secured to the handle, and selectively lockable to the handle with a latch device. The latch device may actuate a ball to engage with and to lock the driving head to the handle.
However, the ball may include only a small curved line or even a point in contact with the driving head, such that the driving head may not be powerfully driven by the handle.
U.S. Pat. No. 6,000,302 to Chiang discloses another typical tools including a rotatable driving head adjustably secured to the handle, and selectively lockable to the handle with a latch device. The latch device may actuate a pawl to engage with and to lock the driving head to the handle.
The ball may include a greater contact area with the driving head than the prior ball structure. However, the pawl may also be easily forced or moved away from the driving head when the driving head is rotated relative to the handle.
U.S. Pat. No. 4,901,608 to Shieh discloses a further typical tools including a rotatable driving head adjustably secured to the handle, and selectively lockable to the handle with a button. The button includes a gear attached thereon and may actuate the gear to engage with and to lock the driving head to the handle.
However, the engagement between the gear and the teeth of the driving head is weak; i.e., the gear may not be solidly engaged with the teeth of the driving head and the gear teeth may be easily damaged, such that the driving torque of the handle onto the driving head may not reach or fulfill the requirement of the users.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional tools having rotatable driving heads.